This assembly is from 1957 from a Raytheon manual, but can be modernized using a BC548, 6 V power supply and common 100 mA relays.
This traditional two-tone alarm configuration with the 4011 integrated circuit was found in a 1998...
This extremely slow circuit produces one pulse per month and can be used in a timer. We found it...
This circuit is from an 80's documentation, making use of PUTs that are not currently common...